As conventional drug administration method, oral administration, rectal administration, intracutaneous administration, and intravenous administration are generally known. Especially oral administration is popularly adopted among others. Oral administration has been defective in that the liver is susceptible to primary metabolism after absorption of the drug, and a higher blood concentration of drug than the necessary level is observed temporarily after oral administration. Furthermore, many cases of gastrointestinal trouble, feeling of vomiting, anorexia and other side effects are reported.
Recently, therefore, with a view to solving these defects of oral administration, the method of percutaneous administration is attracting the general attention as permitting absorption of a drug safely and continuously. Efforts have been made to develop external-use drugs for this purpose, and some products have already been put to the market.
In the drugs for such percutaneous administration, however, percutaneous absorption of the drug is still on a low level in many cases, and the object seems to be far from fully being achieved.
More particularly, normal skin has originally a barrier function of preventing ingression of an exenobiotic substance into the body. A base alone used for ordinary percutaneous administration cannot therefore ensure sufficient percutaneous absorption of effective ingredients blended therein. It is therefore necessary to make contrivances to improve percutaneous absorption of a drug by controlling the barrier function of the horny substance layer of skin. For this purpose, blending of a material known as percutaneous absorption promoter into the base is generally attempted. For example, there have been proposed dimethyl acetamide combined with ethyl alcohol, isopropyl alcohol or myristyl alcohol as an absorption promoter in combination with a lower alkylamide (U.S. Pat. No. 3,472,931), a combination of 2-pyrrolidone, an appropriate oil, and a straight-chain fatty acid with ester of alcohol (U.S. Pat. No. 4,017,641), and a combination of a lower alcohol having a carbon number of from 7 to 20, an aliphatic hydrocarbon having a carbon number of from 5 to 30, an alcohol ester of aliphatic carboxylic acid having a carbon number of from 19 to 26, mono- or di-ether having a carbon number of from 10 to 24, and ketone having a carbon number of from 11 to 15 with water (Japanese Patent Provisional Publication No. 61-249.934).
However, these conventional absorption promoter and absorption promoting compositions cannot as yet be considered to be sufficient in safety of skin. Percutaneous absorption enhancer composition with low irritation to skin (Japanese Patent Provisional Publication No. 2-115,131) has been proposed. In this case also, irritation is observed on the skin of the portion of administration of a subject particularly sensitive to alcohol.
Under such circumstances, these percutaneous administration methods cannot provide sufficient practical merits for use of a drug, and are not therefore as yet satisfactory in drug stability for pharmaceutical purposes, as absorption and low irritation to skin, and manifestation of drug efficacy.
As the example, tulobuterol is a .beta.-stimulant drug having selectively a bronchiectasis function and is known as a therapeutic drug of bronchial asthma, chronic bronchitis, and dyspnea caused by airway obliteration disease. This is in general orally administered in the form of tablets or dry syrup. Orally administered tulobuterol drug has the problem of such adverse side effects as palpitation, defect of circulatory system like increase in cardiac rate, headache, excitement, defect of psycho-nervous system like giddiness and defect of gastric-intestinal disorder like vomiting, anorexia, and other troubles in the psycho-nervous system, and vomiting, anorexia and other troubles in the gastric system. These side effects are considered to attribute to the temporary increase in the drug concentration in blood after oral administration. Continuity of the function is still insufficient in oral drug, and a paroxysm occurring frequently at peep of dawn cannot sufficiently be coped with. As a measure to overcome these defects, therefore, there is a demand for a drug composition permitting a long endurance of the tulobuterol concentration in blood through percutaneous administration, and for this purpose, an external-use drug for percutaneously administering tulobuterol has been proposed (Japanese Patent Provisional Publication No. 63-10,716). The intent of the patent is to prevent temporary increase in the concentration in blood after administration of the drug by using a cream or patch as new method. For the purpose of promoting percutaneous absorption, there can be cited a method of having a composition comprising a lower alcohol, an alcohol having a carbon number of from 7 to 20 or an aliphatic hydrocarbon having a carbon number of from 5 to 30, and water contain effective ingredients (Japanese Patent Provisional Publication No. 61-249,934). This publication discloses applicability of the composition in the form of ointment, plaster, lotion, adhesive tape impregnated form and gel. A transdermal matrix based on a composition comprising polyisobutylene which is a synthetic rubber and tulobuterol which is an effective ingredient is also proposed (Japanese Patent Provisional Publication No. 4-99,720).
However, these conventional methods and compositions therefore cannot as yet be sufficient in stability of drug absorption and irritation to skin, and drug pharmacological a effects.
These circumstances are not limited to above-mentioned case of tulobuterol, but are problems common to various drugs in application.
The present invention was developed to solve the problems in the prior art as described above, and has an object to provide a base composition for percutaneous administration, which increases percutaneous absorption of the drug, and has a low irritation to skin of the portion of administration, and a drug composition for percutaneous administration, using the above composition, excellent in stability.